/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
 *
 * This library is open source and may be redistributed and/or modified under
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_REF_PTR
#define OSG_REF_PTR 1

//#include <osg/Config>

namespace osg {

/** Smart pointer for handling referenced counted objects.*/
template<class T>
class ref_ptr
{
	public:
		typedef T element_type;

		ref_ptr() : _ptr(0) {}
		ref_ptr(T* ptr) : _ptr(ptr) { if (_ptr) _ptr->ref(); }
		ref_ptr(const ref_ptr& rp) : _ptr(rp._ptr) { if (_ptr) _ptr->ref(); }
		template<class Other> ref_ptr(const ref_ptr<Other>& rp) : _ptr(rp._ptr) { if (_ptr) _ptr->ref(); }

		~ref_ptr() { if (_ptr) _ptr->unref();  _ptr = 0; }

		ref_ptr& operator = (const ref_ptr& rp)
		{
			assign(rp);
			return *this;
		}

		template<class Other> ref_ptr& operator = (const ref_ptr<Other>& rp)
		{
			assign(rp);
			return *this;
		}

		inline ref_ptr& operator = (T* ptr)
		{
			if (_ptr==ptr) return *this;
			T* tmp_ptr = _ptr;
			_ptr = ptr;
			if (_ptr) _ptr->ref();
			// unref second to prevent any deletion of any object which might
			// be referenced by the other object. i.e rp is child of the
			// original _ptr.
			if (tmp_ptr) tmp_ptr->unref();
			return *this;
		}

#ifdef OSG_USE_REF_PTR_IMPLICIT_OUTPUT_CONVERSION
		// implicit output conversion
		operator T*() const { return _ptr; }
#else
		// comparison operators for ref_ptr.
		bool operator == (const ref_ptr& rp) const { return (_ptr==rp._ptr); }
		bool operator == (const T* ptr) const { return (_ptr==ptr); }
		friend bool operator == (const T* ptr, const ref_ptr& rp) { return (ptr==rp._ptr); }

		bool operator != (const ref_ptr& rp) const { return (_ptr!=rp._ptr); }
		bool operator != (const T* ptr) const { return (_ptr!=ptr); }
		friend bool operator != (const T* ptr, const ref_ptr& rp) { return (ptr!=rp._ptr); }
 
		bool operator < (const ref_ptr& rp) const { return (_ptr<rp._ptr); }


	// follows is an implmentation of the "safe bool idiom", details can be found at:
	//   http://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Safe_bool
	//   http://lists.boost.org/Archives/boost/2003/09/52856.php

	private:
		typedef T* ref_ptr::*unspecified_bool_type;

	public:
		// safe bool conversion
		operator unspecified_bool_type() const { return valid()? &ref_ptr::_ptr : 0; }
#endif

		T& operator*() const { return *_ptr; }
		T* operator->() const { return _ptr; }
		T* get() const { return _ptr; }

		bool operator!() const   { return _ptr==0; } // not required
		bool valid() const	   { return _ptr!=0; }

		T* release() { T* tmp=_ptr; if (_ptr) _ptr->unref_nodelete(); _ptr=0; return tmp; }

		void swap(ref_ptr& rp) { T* tmp=_ptr; _ptr=rp._ptr; rp._ptr=tmp; }

	private:

		template<class Other> void assign(const ref_ptr<Other>& rp)
		{
			if (_ptr==rp._ptr) return;
			T* tmp_ptr = _ptr;
			_ptr = rp._ptr;
			if (_ptr) _ptr->ref();
			// unref second to prevent any deletion of any object which might
			// be referenced by the other object. i.e rp is child of the
			// original _ptr.
			if (tmp_ptr) tmp_ptr->unref();
		}

		template<class Other> friend class ref_ptr;

		T* _ptr;
};


template<class T> inline
void swap(ref_ptr<T>& rp1, ref_ptr<T>& rp2) { rp1.swap(rp2); }

template<class T> inline
T* get_pointer(const ref_ptr<T>& rp) { return rp.get(); }

template<class T, class Y> inline
ref_ptr<T> static_pointer_cast(const ref_ptr<Y>& rp) { return static_cast<T*>(rp.get()); }

template<class T, class Y> inline
ref_ptr<T> dynamic_pointer_cast(const ref_ptr<Y>& rp) { return dynamic_cast<T*>(rp.get()); }

template<class T, class Y> inline
ref_ptr<T> const_pointer_cast(const ref_ptr<Y>& rp) { return const_cast<T*>(rp.get()); }

}

#endif
